Composites, such as reinforced resins and plastics, are widely used in various industries. Advanced composites, including high-performance reinforced resin and plastic systems, are used extensively in the automotive and aerospace industries to create composite parts capable of meeting the more demanding requirements of these applications.
Many manufacturing methods exist for the production of composite parts. However, one of the more common methods used in the automotive and aerospace industries is the pre-preg lay-up method. According to this method, a pre-preg (i.e., a fiber cloth or network pre-impregnated with a resin) is laid-up on a molding tool, and then cured to take on the shape of the molding tool, thereby forming the shape of the desired composite part. After the curing process is complete and the pre-preg is cured to form the desired part shape, the finished part must be released from the mold. However, the curing process can cause the pre-preg to stick to the molding tool, making it difficult to subsequently release the finished part from the tool.
To address this post-cure release issue, liquid release agents are sometimes coated or sprayed on the tool prior to laying-up the pre-preg for curing. However, these liquid release agents have a number of problems. For example, the liquid release agent may solidify and the solidified release material may remain on the molding tool after part manufacture and release. This residual release agent must be cleaned off the molding tool before the tool can be used to make another composite part, thus increasing the time and labor required to repeat the manufacturing process. Additionally, the solidified release agent may remain on the composite part after removal from the mold. This residual release agent must be removed from the part before the part can be painted or bonded to another material/component. Typically, the residual release agent is removed from the part surface by abrasion, shot blasting, etc., which can cause surface defects or imperfections which, in turn, cause defects or imperfections in the paint finish making the part unusable and necessitating part reworking. Further, some liquid release agents include volatile compounds (e.g., solvent-based liquid release agents), and therefore must be stored and applied very carefully in order to alleviate health risks. For example, solvent-based liquid release agents typically require special workstation ventilation equipment and personal protective equipment, which further increases cost.